8707
Stepwise Metal Chelate Formation. Isolation of the Intermediates ( n-C,H,) Fe (CO) ,[ (C,H,) J' (CH, 1, P (C,H, ) ( n = 1, 2, 3) and Their Reactions as Ligands'
+
Madeline L. Brown,2 Jeffrey L. Cramer, John A. Ferguson, Thomas J. Meyer,* and Neil Winterton Contribution from the Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27514. Received M a y 3, 1972 Abstract: From reactions between (a-C5H5)Fe(C0)?(OC(CH3)2)+ and the di(tertiary phosphine) ligands Ph2Pin (CH2),PPh2(n = 1,2, 3; Ph is phenyl) we have isolated the 1 :1complexes, (a-C5H6)Fe(C0)~(Ph2P(CH2).PPhz)+, which a donor site on the di(tertiary phosphine) is not bound. The 1 :1 complexes can react as ligands and we have
or used this reactivity to prepare symmetric, Le., [(~-CSH~)F~(CO)Z(P~~P(CHZ)~PP~Z)F~(CO)Z(~-C~H~)I(PF~ -(C10& (n = 1, 2, 3), and mixed-metal, i.e., { [(.rr-C5H5)Fe(CO)z(Ph2P(CHz),PPhz)lzCoC1z~ (PF& or -(ClO& (n = 2, 3), complexes in which metal ions are linked by bridging ligands. 2J-Dithiahexane and pyrazine have also been used as bridging ligands in the complexes { [( .rr-C5H5)Fe(C0)&(CH3SCH2CH1SCH3) 1 (c104)?and { [(x-C5H5)Fe(C0)&NC4H4N)] An efficient light-catalyzed path for the conversion of the 1:1 complexes into (+ hv) (T-C~H~)F~(CO)(P~ZP(CHZ)~chelated complexes has been found: (a-C5H5)Fe(C0)2(Ph2P(CH~)nPPh~)+ PPh2)+ CO ( n = 1 or 2).
-
+
e have described the preparation of (a-C5H5)Fe(C0),(0C(CH3),)+ by the reaction3
(C0)2(Ph2P(CHz).PPhz)+( n = 1, 2, 3 ; reaction 1) can themselves react as ligands by using the uncoordinated donor site on the bound di(tertiary phosphines). Part 2Fe3+ [(*-C~HdFe(C0)z]r 2(CH3)zCO + of this work has appeared in a preliminary communica2FeZ++ 2( R-C~H~)F~(CO)~(OC(CH~)~)+ tionS5 The bound acetone molecule in ( a-CjH6)Fe(C0)2Results and Discussion (OC(CH&)+ is easily displaced by a variety of neutral The reactions which have been carried out using the and anionic ligands to give (a-C5Hj)Fe(C0),L+ (L = di(tertiary phosphine) ligands Ph2P(CH2),PPhz ( n = neutral ligand) and ( .rr-C6H6)Fe(C0),X (X = anionic 1, 2, 3) are summarized in Scheme I. Some of the comligand). Using mild conditions only the coordinated plexes which appear in the scheme, or closely related acetone molecule is labile. The property of having a complexes, have been reported previously as products single labile coordination site introduces an element of of a variety of reaction^.^-^ Synthetically the scheme synthetic control into the stepwise reactions between has the advantage of offering a common synthetic route ( a-C5H5)Fe(C0)2(0C(CH3)2)+ and potentially chelating to a variety of products using a common intermediate, ligands, e.g. ( a-C5H5)Fe(C0)2(0C(CH3)2)+, and it allows synthetic fast (~-CsHs)Fe(C0)2(0C(CH3)2)f+ PhzPCHzCHzPPhz ----f control at each step. Ligands other than the di(tertiary phosphines) can be used; complexes having either (T - C ~ H S ) F ~ ( C O ) ~ ( P ~ ~ P C H ~ C +HCH3)zCO ~ P P ~ Z ) +(1) 2,5-dithiahexane, { [( n-C6H6)Fe(C0)z]2(CH3SCHzCHzslow ( T-C~H~)F~(CO)~(P~ZPCHZCHZPP~Z)+ + SCH3>1(C104)2, or pyrazine, { [(a-C5H5)Fe(C0)2]2(W-C~H~)F~(CO)(P~ZPCHZCHZPP~Z)+ + CO (2) (NC4H4N)](C104),, as the bridging ligand have also (Ph is phenyl) been prepared. The syntheses outlined in Scheme I are dependent on the fact that the starting complex, ( a-C6The initial step, displacement of coordinated acetone H6)Fe(CO),(OC(CH3),)+, has a single, labile coordi(reaction l), is rapid while the closing of the chelate nation site. A pattern of reactions like Scheme I should ring in the second step involves displacement of coexist for other metal complexes with similar lability ordinated CO (reaction 2), and it is slow. This pattern Spectral data for the complexes reproperties. lo, in the relative rates of reactions 1 and 2 is opposite that ported here are given in Table I. In cases where pmr normally observed for stepwise metal chelate formation, spectra are reported, the ratios of a-C6H5to ligand prowhere chelate ring closure is the rapid step.4 As retons were determined by integration, and the values so ported here, the relative slowness of reaction 2 using obtained compared satisfactorily with calculated values. mild reaction conditions allows the isolation of comIn two cases the a-C5H6 resonances were split, apin plexes like ( a-C6H6)Fe(C0)2(PhzPCHzCHzPPh2)+ which one of the donor sites on a coordinated ligand is ( 5 ) M. L. Brown, T. J. Meyer, and N. Winterton, Chem. Commun., 309 (1971). not bound. The subsequent chelation step is much (6) J. A. Ferguson and T. J. Meyer, Inorg. Chem., 1 1 , 631 (1972); slower although an efficient light-catalyzed path for J. A. Ferguson and T.J. Meyer, Chem. Commun., 1544 (1971). (7) P. M. Treichel, R. L. Shubkin, K. W. Barnett, and D. Reichard, chelation does exist. The complexes (a-C5H6)Fe-
+
+
(1) Presented in part at the 161st National Meeting of the American Chemical Society, Los Angeles, Calif., March 1971, (2) National Science Foundation Undergraduate Research Participant, summer, 1970. (3) E. C. Johnson, T. J . Meyer, and N. Winterton, Inorg. Chem., 10, 1673 (1971); Chem. Commun., 934 (1970). (4) K. Kustin and J. Swinehart, Progr. Inorg. Chem., 13, 107 (1970).
Inorg. Chem., 5, 1177 (1966). (8) R. J. Haines and A. L. du Preez, ibid., 11, 330 (1972).
(9) R. B. King, K. H. Pannell, C. A. Eggers, and L. W. Houk, ibid., 7, 2353 (1968). (10) R. J. Mawby, D. Morris, E. M. Thorsteinson, and F. Basolo, ibid., 5, 27 (1966). (11) S. A. Adeyemi, J . N. Braddock, G. M. Brown, J . A. Ferguson, F. J. Miller, and T. J. Meyer, J . Amer. Chem. Soc., 94, 300 (1972).
Table I. Spectral Properties of the Compounds [(T-C~H~)F~(C~)Z(P~~PCHZPP~Z)IC~O~ 2054, 2012O [( ?r-CjHj)Fe(CO)(PhzPCHzPPhz)]ClO4 1982~ [( ?r-CsHs)Fe(CO)Z(PhzPCHzPPhz)Fe(C0)2( ~CsHs)](BPhr)z 2055, 2015a [(~-CsHs)Fe(C0)z(PhzPCHzCHzPPhz)lClOa 2057, 2014" [(T-C~H~)F~(CO)(P~ZPCHZCHZPP~Z)]C~O~ 1980" [(n-CjHs)Fe(CO)z(PhzPCHzCHzPPhr)Fe(CO)z( i~-CsHs)](ClOa)z 2050, 199& [(.R-C~H~)F~(CO)Z(P~ZPCH~CHZCHZPP~~)]C~O~ 2059, 2014" [( n-CsHs)Fe(CO)z(PhzPCHzCHzCHzPPhz)Fe(CO)z( ~ C s H s ) lC104)z ( 2050, 2009" [( ~-C~H~)F~(C~)Z(CH~SCHZCHZCH~)F~(CO)Z( i~CsHs)](C104)~ 2071, 2033. [( * - C ~ H ~ ) F ~ ( C O ) Z ( N C ~ H ~ N ) F ~ ( C O ) Z ( * - C ~ H ~ ) I ( C ~ ~2067, ~ ) Z 2O3lc ( [( ?r-CjH5)Fe(CO)z(PhzPCHzCH~PPhz)l~CoC12] (PF& 2061, 2O1la
{ [(~-C~H~)F~(CO)~(P~~PCH~CHZCH~PP~Z)]~COC~~) (PF& 2056, 2011" a
at
In dichloromethane. 8.00. e Multiplet.
b
In acetone-& relative to acetone-& at
7
7.93.
c
350 sh
4.48, 4.49b 4.75b 4.99d 4.50b 4.90b 4.8V 4.47b 4.85, 4.87d 4.52d 4.11d
350 sh 350 sh
2.48, 2.68 2.70 2.45: 2.93, 3.07 2.50, 2.71 2.45 2.56 2.30, 2.38 2.43
340 sh, 595, 640 sh. 650. 715 340 sh, 597, ' 640 sh, 660, 690
In Nujol mulls.
d
In acetonitrile-& relative to acetonitrile-dz
7
parently by 31P splitting. We have been unable to prepare an analytically pure sample of the complex [( a-C5H,)Fe(C0)2(Ph2(CH2)3PPhz)]+ as either its perchlorate or hexafluorophosphate salts. Chelation. The 1 :1 complexes, (.rr-CbHb)Fe(CO)z(Ph2P(CHz)nPPhz)+ (n = 1, 2, 3), are stable in dichloromethane solution for days. Chelation does not occur even if the dichloromethane solutions are refluxed for periods as long as 5 hr in the absence of light. It is not surprising that the chelation reactions are slow since they involve the displacement of CO. Substitution for CO by other ligands in complexes of the types ( 7r-C5Hj)Fe(C0)2X and (T - C ~ H ~ ) F ~ ( C O ) is ~ Lknown + to be ~10w.7~ 12 For the complexes with n = 1 or 2 an efficient lightcatalyzed path exists
hv
+
( T - C ~ H ~ ) M ~ ( C O )+ ~ P P( ~?r-C6H5)Mn(CO)PPh3 ~ CO
which reacts rapidly with the free ligand
+
(?r-C5H5)Mn(CO)PPh3 PPh3 +(?r-CjH5)Mn(CO)(PPh3)2
hv
( T-C~H~)F~(CO),(P~ZP(CHZ),PP~~)+ +
chelated complexes. This reaction was not studied in detail. The light-catalyzed path for chelate ring closure is an efficient photoreaction from our qualitative observations. The mechanism for these reactions may be the same in general detail as that found for the lightcatalyzed displacement of CO in the simple binary metal carbonyls13 and specifically for the complex ( T - C ~ H ~ ) M ~ ( C O )l 4~ Pwhich P ~ ~ , is essentially isoelectronic with the iron 1 : 1 complexes. In this mechanism, the initial absorption of light is followed by ejection of a CO group giving a lower coordinated (or weakly solvated) intermediate
+
interesting feature of this chemistry for the iron 1 : 1 complexes is that capture of the lower coordinated intermediates, if formed, occurs by an internal reaction (chelate ring formation) rather than by an external bimolecular reaction.
The ( T-C~H~)F~(CO)(P~ZP(CHZ)~PP~Z)+ CO ( n = 1 or 2)
Using a 275 W GE sun lamp in contact with the reaction flask, a solution ca. 2 X M in (a-C5Hj)Fe(C0)2(Ph2PCH2PPh2)+ in dichloromethane was completely converted into the chelated complex after 3 min of photolysis. The progress of the photolytic reactions in acetone-ds was monitored by pmr and in dichloromethane by infrared spectra. No attempt was made to isolate the chelated complexes. Both complexes (n = 1, 2 ) have been prepared by other synthetic routes',* and they were characterized by their spectral properties as summarized in Table I. The initial light induced chelation step is followed by a slower photodecomposition reaction in which CO is lost from the (12) A. Wojcicki and F. Basolo, J . Amer. Chem. Soc., 83, 525 (1961).
All attempts to prepare the chelated complex ( 7r-C5H5)Fe(CO)(Ph2P(CH2)3PPh2)+ were unsuccessful. Our (13) W. Strohmeier, Angew. Chem., Znt. Ed, Engl., 3,370 (1964). (14) W. Strohmeier and C. Barbeau, 2. Nuturforsch. B, 17. 848 (1962).
Journal of the American Chemical Society / 94:25 1 December 13, 1972
8709
inability to prepare this complex may reflect a lesser stability for the six-membered chelate ring system, l5 although it may be that chelate ring closure for the longer ligand is not competitive with recapture by CO. Ligand Bridged Complexes. At room temperature the 1 : 1 complexes, ( a-C6H5)Fe(C0)z(PhzP(CH2)nPPh2)+ ( n = 2 or 3) react rapidly with CoClz.6Hz0 (or with anhydrous cobalt(I1) chloride) in acetoneethanol mixtures, uiz.
+
2( a-CoH5)Fe(CO)z(Ph2P(CH2)nPPh2)fCo(I1)
+ 2C1- +
and their most interesting property is that they link metal centers. In the bridged complexes the metal centers are apparently isolated electronically. However, the reactions summarized in Scheme I are flexible synthetically and by varying the bridging ligand and added metal ion materials may be isolated which have, to some extent, the combined properties of both metal centers in either ground or excited states. We are currently exploring this possibility.
Experimental Sectionz0
[(a-C5H5)(C0)2Fe(Ph2P(CH2)nPPh2)]2CoC12z+ Bis( ?r-cyclopentadienyldicarbonyliron)(Alfa Inorganics) and 1,2( n = 2, 3) bis(dipheny1phosphino)ethane (Arapahoe Chemicals) were used without further purification. The di(tertiary phosphine) ligands,
The bridged metal complexes can be isolated as perbis(dipheny1phosphino)methane and 1,3-bis(diphenylphosphino)chlorate or hexafluorophosphate salts. We have been propane, were prepared as described in the literature.21 Infrared spectra were recorded on Perkin-Elmer 421 or Perkinunable to isolate the analogous complex with n = 1, Elmer 257 spectrophotometers. Pmr spectra were obtained using probably because of increased steric repulsions ima JEOL C 6 0 H L spectrometer. Ultraviolet-visible spectra were posed by the shorter bridging ligand. We have obrecorded on either Cary 14, Cary 17, or Unicam spectrophotometers. tained spectral evidence that a relatively slow reaction Elemental analyses were performed by either Galbraith Laboradoes occur when both (a-C5H5)Fe(C0)z(PhzPCH2- tories, Knoxville, Tenn., or Meade Microanalytical Laboratory, Amherst, Mass. Iron analyses were carried out as described prePPhz)+ and anhydrous cobalt(I1) chloride are present viously,zzand cobalt(I1) was determined spectrophotometrically in in ethanol-acetone solution. The complexes are easily the presence of thiocyanate ions.23 decomposed in solution. If a few drops of water are Preparations. Warning! Several of the following preparations added to acetone solutions of [( a-CjH5)Fe(C0)z(PhzP- call for the use of solutions containing perchlorate ions and labile organometallic complexes, followed by the isolation of organo(CHz)nPPhz)]2CoC1z2+, an immediate reaction occurs giving cobalt(I1) and ( a-CjHj)Fe(CO)Z(PhzP(CHz)n- metallic perchlorate salts. The solutions and/or the salts may be explosive, and due care should be taken in working with them. PPh2)+. The pmr spectra of the cobalt complexes show All preparations in which the acetone complex, ( ?r-CjH5)Fe(C0)2extensive paramagnetic shifts as expected. 16,l7 Un(OC(CH&)+, is used were carried out under an atmosphere of nitrogen. fortunately, we have been unable to assign these spectra (1) The Acetone Intermediate (?r-CjHS)Fe(C0)2(OC(CH3)2) +. with any certainty. In a typical experiment [ ( T - C ~ H ~ ) F ~ ( C (0.525 O ) ~ ] ~g, 1.51 mmol) The cobalt-iron mixed-metal complexes have properand anhydrous ferric perchlorate (1.766 g,4.9 mmol) were disties characteristic of the isolated metal ions. We have solved together in deaerated acetone (20 ml). After 20 min the found no evidence that there is a significant electronic solution was reduced in volume to ca. 1 ml using a stream of nitrogen. The residue was extracted with dichloromethane (3 X 15 ml) interaction between the metal centers. For the CO and the dichloromethane washings were chromatographed twice on groups bound to iron, the v(C0) values are only slightly Florisil (60-100 mesh, 3 X 1 cm). The chromatographed solution shifted from the values found for the uncomplexed ions was evaporated to ca. 5 ml. At this point solutions contain between ( a-C5H5)Fe(CO)z(PhzP(CHz),PPhz)+ ( n = 2, 3) (Table 30 and 7 0 x of the acetone complex, (?r-CaHj)Fe(C0)2(0C(CH3)2)+, I). For the mixed-metal complexes the pattern of based on the amount of [(?r-CSHs)Fe(C0)2]2used initially, and they are free of iron(I1) and iron(II1). In later preparations in which electronic bands in the visible region of the spectrum the acetone complex is used, solutions werz prepared as described (Table I) is essentially the same as that found for Coabove, and the amount of the acetone complex present was esti(La,at 675, 645 (sh), and 594 nm in di(PPh3)zC1z18 mated from the amount of [( ?r-C5Ha)Fe(CO)~]2 used initially. chloromethane) which indicates that the ligand geome(2) 1 :1 Complexes [(n-CjH5)Fe(CO)r(Ph2P(CH2),PPh2)]C104 ( n = 1,2,3). A solution of the acetone intermediate, prepared as try at cobalt is tetrahedral.lQ The bands which apdescribed above, was added to bis(diphenylphosphino)methane, pear at 350 nm (shoulder) for the iron 1 : 1 complexes PhtPCH2PPhZ (0.9238 g, 2.4 mmol, ca. eightfold excess), in benzene are nearly unaffected by complexation to cobalt. We (10 ml). The solution was stirred for 3 hr and then added slowly have found no bands in the region 200&220 nm which to ether (80 ml) which precipitated [(?r-CjHj)Fe(C0)2(Ph2PCH2can be attributed to electron transfer between the metal PPh2)](C10a) as a yellow powder. The product was washed with benzene (5 ml), ether (20 ml), and then dissolved in acetone, filtered, centers. The available spectral evidence indicates that and reprecipitated with ether, giving the yellow product in 37% in the cobalt-iron complexes, the saturated bridging yield. Anal. Calcd for (?r-C5H5)Fe(C0)2(Ph2PCH2PPhx)C104: ligands effectively shield the metal centers from any C, 58.18; H, 4.09; Fe, 8.45. Found: C, 57.46; H, 4.20; Fe, significant interaction. 7.42. The analogous complexes [( n-C5H5)Fe(C0)2(Ph2P(CH2),In summary, the complexes ( n-C5H5)Fe(CO)n(PhzP- PPh2)](C104) ( n = 2, 3) were prepared similarly using 1,2-bis(dipheny1phosphino)ethane and 1,3-bis(diphenylphosphino)propane in (CHz)nPPhz)+( n = 1, 2, 3) can function as ligands be5-10 molar excesses. Yields of from 30 to 63 based on the amount cause of the unbound donor site on the coordinated diof [ ( ? T - C ~ H ~ ) F ~ ( Cused O ) ~initially ]~ were obtained. Anal. Calcd (tertiary phosphine). As ligands, in either symmetrical, for (?r-CjH5)Fe(C0)2(PhzPCH2CH2PPh2)C104: C, 58.73 ; H, [(a-CjHj)Fe(CO)z(Ph2P(CH2)nPPhz)Fe(C0)2( a -C,H5)]2+ 4.34; P, 9.18; C1, 5.25. Found: C, 57.86; H, 4.50; P, 8.91; ( n = 1, 2, 3), or mixed-metal, [ ( T - C ~ H ~ ) ( C O ) ~ -C1, 4.60. Calcd for ( ?r-C5HS)Fe(C0)2(Ph2PCH2CH2CH2CH2PPh2)C104: C, 59.28; H,4.50; Fe, 8.10. Found: C, 57.60; H, 5.34; Fe,7.15. Fe(PhzP(CHz),PPhz)]2CoClz2+ ( n = 2, 3), complexes, (3) 2 :1 Complexes. (a) { [(n-CsHj)Fe(CO)s]2(Ph2P(CH,),they appear to behave as typical alkyl-aryl phosphines, PPh2))(C104)z( n = 2, 3). To a solution of the acetone intermedi(15) F. J. C. Rossotti in “Modern Coordination Chemistry,” J. Lewis and R. G. Wilkins, Ed., Interscience, New York, N. Y.,1960, p 60. (16) W. Dew. Horrocks, Jr., and E. S. Greenberg, Inorg. Chem., 10,
2190 (1971). (17) R. H. Fischer and W. Dew. Horrocks, Jr., ibid., 7, 2659 (1968). (18) C. Simo and S. Holt, ibid., 7, 2655 (1968). (19) G. Garton, D. E. Hem, H. M. Powell, and L. M. Venanzi, J . Chem. SOC.,3625 (1963).
ate in ca. eightfold excess was added 1,3-bis(diphenylphosphino)(20) Ph is used here as an abbreviation for -CEHS. (21) W. Hewertson and H. R. Watson, J . Chem. Soc., 1490 (1962). (22) J. A . Ferguson, Ph.D. Thesis, University of North Carolina, 1971; W. B . Fortune and M. G. Mellon, Ind. Eng. Chem., Anal. Ed., 10, 60 (1938). (23) R. E. Kitson, Anal. Chem., 22, 664 (1950).
8710 50-50 mixture of benzene-acetone (5 ml), dropwise with stirring propane (0.0495 g, 0.12 mmol) in benzene (4 ml). The solution color over a 10 min interval. After 12 hr benzene was added (5 ml), and changed from red to yellow after stirring for 2 hr, and an oil formed. the golden precipitate was collected and washed with dichloroAcetone (3 ml) was added to dissolve the oil. The solution was then methane (6 X 5 ml) giving ( [(n-CaH5)Fe(CO)~]2(NC4H4N))(C101)2 added dropwise to ether giving ( [(T-C~H~)F~(CO)Z]Z(P~ZP(CH~)~in 38% yield. Anal. Calcd for ( [(n-C5Ha)Fe(C0)2]2(NC4H4N))PPh2)}(C104)2as a yellow powder. The complex was collected and (ClO&: C, 34.21; H, 2.08; C1, 11.22; N, 4.43. Found: C, washed with benzene (5 ml) and ether (20 ml). It was then dissolved 33.92; H , 2.40; C1, 11.00; N, 4.32. in acetonitrile, filtered, reprecipitated with ether, collected, and (4) Complexes with Cobalt(II), I [(n-C,Hj)Fe(Co),(Ph2P(CH2)~air-dried giving the yellow solid in 87% yield. Anal. Calcd for PPhz)]2CoC12](C104)a or -(PF& ( 1 1 = 2, 3). T o anhydrous cobalt(1I) ( [(n-C5H5)Fe(C0)~]~(Ph~PCH2CH2PPh2)}(C1O4)~: C, 51. l o ; chloride (0.0247 g, 0.19 mmol) in ethanol (1 ml) was added [(nH , 3.75; P, 6.43; C1, 7.32; Fe, 11.56. Found: C, 49.50; H, CjHj)Fe(C0)2(Ph~PCHCH~PPh2)]PF6 (0.195 g, 0.266 mmol) in 3.87; P, 6.47; C1, 7.19; Fe, 10.72. The 2 : l complex of 1,2-bisacetone (3 ml) with stirring. After 2 hr, ether (25 ml) was added (dipheny1phosphino)ethane was prepared similarly using ca. a which precipitated a turquoise solid. The solid was dissolved in fourfold excess of the acetone intermediate. It was obtained in 83 % dichloromethane, filtered, and reprecipitated with ether. ( [( T yield. Anal. Calcd for ( [(n-CbHe)Fe(CO)~]2(Ph~PCH2PPhz) )CjHj)Fe(CO)2(Ph2PCH?CH~PPh2)]2CoC12 i (PF6)2 was recrystallized (C104): C, 50.50; H , 3.61; P, 6.51; CI, 7.45. Found: C, 51.85; from chloroform-ether giving a 53 yield. A m l . Calcd for { [ ( T H , 3.81; P, 6.56; C1, 7.49. C5Ha)Fe(C0)2(Ph~PCH2CH2PPh~)]2CoC1~ ) (CIO& : C, 53.58; H, T o the acetone (b) { [(T-C~H~)F~(C~)~]~(P~~PCH~PP~Z)}(BP~~)~. 3.95; C1, 9.59; Co, 3.98. Found: C, 54.34; H , 4.05; C1, 10.53; intermediate in ca. ninefold excess was added bis(dipheny1phosCo, 3.77. The complex { [(n-CjHj)Fe(CO)z(PhzP(CH2)sPPh2)12phino)methane (0.0794 g, 0.206 mmol) in benzene (3 ml). The CoCh ) (PF& was prepared similarly in 48 Z yield. Anul. Calcd solution was stirred for 2 hr. The yellow 2 : l complex was precipifor { [ ( T - C ~ H ~ ) F ~ ( C ~ ) ~ ( P ~ ~ P C H ~ C H ] (PF6)2: ~ P P ~Fe, ?)~~COC~~ tated using ether (ca. 250 ml), collected, and washed with benzene 6.98; Co, 3.69. Found: Fe, 6.96; Co, 3.45. (10 ml) and then with ether (20 ml). This perchlorate salt is explo(5) Conversion to Hexafluorophosphate and Tetraphenylborate sioe when dry and should not be isolated! Rather, before the solid Salts. The perchlorate salts were dissolved in a minimum of dried it was dissolved in acetonitrile (10 ml), added slowly to 20 ml acetone or acetonitrile, and after filtering the solutions they were of an aqueous solution of sodium tetraphenylboron (0.34 g, 1 mmol), added to aqueous solutions containing large excesses of ammonium and precipitated by the addition of ether (500 ml). The solid which hexafluorophosphate or sodium tetraphenylboron, precipitated was dissolved in acetonitrile, filtered, and reprecipi( 6 ) Chelated Complexes, [ ( R - C ~ H ~ ) F ~ ( C O ) ( P ~ ~ P ( C H ~ ) ~ P P ~ ~ ) ] + . tated by adding ether, collected, and air-dried giving the orange Solutions of the 1 : 1 complexes [(n-CjH5)Fe(CO)p(Ph~P(CH~),Ph?)Jin 3 9 z yield. solid { [(a-CbHj)Fe(CO)2]~(Ph2PCH2PPh2)}(BPhr)2 (PF6) or -(C104) ( 1 2 = 1, 2) in dichloromethane or acetone-da Anal. Calcd for { [( R-C~H~)F~(CO)~]Z(P~ZPCHZPP~~) ) (BPh4)2: C, M ) were irradiated using a GE 275W sunlamp. (3 x 10-4-6 x 75.92; H, 5.23; P, 4.51; Fe, 8.11. Found: C, 76.35; H , 5.45; The irradiations were carried out for varying lengths of time, from P, 4.63; Fe, 8.15. a few seconds to as long as 10 min. The progress of the reactions (c) { [(n-CjHs)Fe(C0)2]z(CH3SCH2CH2SCH3)) (C10&. To the in dichloromethane was followed by infrared spectroscopy in the acetone intermediate in ca. sixfold excess was added dithiahexane, region from 2200 to 1800 cm-1 and in acetone-de by pmr measureCHaSCH2CH2SCH3(0.24 mmol), in a 1 : l volume mixture of ments. benzene-acetone. The dithiahexane solution was added dropwise with stirring over a 10 min interval. After 3 hr benzene (5 ml) was Acknowledgments. Acknowledgments are made to added. The solution was allowed to stand for 12 hr, and the golden the U. N. C. Materials Research Center through Conprecipitate was collected, washed with benzene (5 ml) and ether (20 ml), and air-dried giving an 81 yield of { [(n-CsH5)Fe(C0)2]~- tract SD-100 with the Advanced Research Projects (CH3SCH2CH2SCH3) }(C101)2. Anal. Calcd for ( [( n-CaHj)FeAgency, to the National Science Foundation through ( C O ) ~ ] Z ( C H ~ S C H ~ C H Z S)(ClO&: CH~) C, 31.92; H, 3.28; Cl, No. GP17083 and GY7311, and to the Petroleum Grant 10.47; S, 9.47. Found: C, 32.19; H, 3.29; Cl, 10.32; S, 9.57. Research Fund administered by the American Chemi(d) ( [(T-C~HJF~(CO)~]~(NC~H~N)(C~O~)~. To the acetone incal Society for support of this research. termediate in ca. fourfold excess was added pyrazine, dissolved in a
Journal of fhe American Chemical Society
1 94:25 1
December 13, 1972
